/Engine/Source/Editor/SceneOutliner/Public/SceneOutlinerGutter.h
Start a new drag/drop operation for this widget
virtual [FReply](API\Runtime\SlateCore\Input\FReply) OnDragDetected ( const [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) & MyGeometry, const [FPointerEvent](API\Runtime\SlateCore\Input\FPointerEvent) & MouseEvent )